HYGROMETRICAL TABLES. lv 



The vapor pressures in the tables here given are expressed in standard 

 manometric units. 



TABLE 69. 



Table 69. Pressure cf aqueous vapor over ice. English measures. 



The pressures, computed by equation (3) above, are given to 0.00001 

 inch for each degree of temperature from — 6o° to — 15 , for each half 

 degree from — 15 to ±o°, and for each tenth of a degree from ±o°o to 

 + 320. 



TABLE 70. 



Table 70. Pressure of aqueous vapor over water. English measures. 



This table has been computed by converting Table 72 into English 

 units. The temperature argument is given for every 0.1 from 32.0 to 214.9 

 F. The vapor pressures are to 0.0001 inch from 32.0 to 130^9, F., and to 

 0.00 1 inch from 130^0 to 2I4°9 F. 



TABLE 71. 



Table 71 . Pressure of aqueous vapor over ice. Metric measures. 



The pressures, computed by equation (2) above, are given to the near- 

 est 0.000 1 mm. for each degree of temperature from — 70 to — 50 , for 

 each half degree from — 50 to — 35 , and each tenth of a degree from 

 — 35°o to ± o°o. 



TABLE 72. 



Table 72. Pressure of aqueous vapor over water. Metric measures. 



The pressures, computed by equation (1) above, are given for each 

 tenth of a degree to 0.001 mm. from o?o to50°9, and too?oi mm. from 50°o 

 to ioo?9. They are given for each degree to 0.1 mm. from ioo° to 189 , and 

 in millimeters from 190 to 374°. 



TABLES 73, 74. 



Table 73. Weight of cubic foot of saturated aqueous vapor — English meas- 

 ures. 



Table 74. Weight of a cubic meter of saturated aqueous vapor — Metric 

 measures. 



For many years it has been customary to assume that the specific 

 gravity of water vapor relative to dry air is a constant whose theoretical 

 value computed from the accurately known densities of its constituent gases 

 is 0.622 1. Direct experimental determinations of the specific volume of dry 

 saturated steam (as yet but few observations are available at moderate 

 temperatures) show conclusively (1) that this theoretical specific gravity is 

 true only for saturated vapor at very low temperatures or when the vapor 

 is in a very attenuated state of partial saturation; (2) that at increasingly 

 higher temperatures the specific gravity is increasingly greater than 0.6221. 

 These assertions are in accord with the values of weight per cubic foot of 



